Which infections may complicate a lung transplantation?

Updated: Aug 19, 2019
  • Author: Bryan A Whitson, MD, PhD; Chief Editor: Mary C Mancini, MD, PhD, MMM  more...
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Answer

Infection is the leading cause of death in lung transplant recipients. Factors that increase a patient's susceptibility to infection after transplant include immunosuppression, reduced mucociliary clearance, decreased cough reflex resulting from denervation, and interruption of lymphatic drainage. For more information, see Infections After Solid Organ Transplantation.

Bacterial/viral pneumonia

Bacterial pneumonias are the most common infection following lung transplantation [57] and occur in more than 35% of patients during the first year after the transplant (highest incidence is during the first month posttransplant). Bacterial pneumonias remain a major infectious complication throughout the patient's life. The donor lung is affected more commonly. Gram-negative organisms are most common, especially Enterobacter and Pseudomonas. Bronchitis secondary to Pseudomonas species or Staphylococcus aureus infection also is observed. Bacterial pneumonia typically manifests radiographically as a lobar or multilobar consolidation.

Viral pneumonias develop in approximately 11% of patients who have undergone lung transplants, and they occur at any time following transplantation.

Opportunistic infections

Opportunistic infections also are common after lung transplant surgery (34-59% of patients), but the infections do not seem to affect overall patient mortality rates.

CMV infection

CMV is the second most common cause of pneumonia in patients who have received lung transplants, and it is the most common opportunistic infection (35-60% of opportunistic infections). [57] CMV is the most significant viral infection, and it usually occurs 1-4 months after the transplant. Primary infection is the most serious and is observed in 50-100% of patients who are seronegative who receive grafts from a donor who is seropositive. In patients who are seropositive, secondary CMV infection develops from reactivation of latent disease following the institution of immunosuppressive therapy or from infection with a different strain of CMV.

Infected patients may be asymptomatic or may develop a fulminant pneumonia, possibly with extrathoracic findings such as retinitis, hepatitis, and gastritis. Presenting symptoms include dyspnea, fever, and cough. The diagnosis of CMV pneumonia can be made by bronchoscopy with lavage and biopsy. Prophylactic therapy with acyclovir and immune globulin has not reduced the incidence of CMV infection in patients who have undergone transplant procedures.

The most common finding on chest radiographs in patients with CMV infection is diffuse parenchymal haziness. CT scan findings in patients with CMV infection include areas of ground-glass attenuation; reticulation; multiple, small, ill-defined 1- to 3-mm nodules; and, even less commonly, areas of dense consolidation.

A retrospective study found that CMV replication in the lung allograft is common following lung transplantation and increases the risk of bronchiolitis obliterans syndrome. [58] Longer antiviral prophylaxis strategies may suppress CMV, leading to improved long-term outcome.

Herpes simplex virus infection

A less common cause of viral infections includes the herpes simplex virus (HSV). Patients with HSV infection present with fever, cough, and dyspnea, but they demonstrate symptomatic improvement after therapy with intravenous acyclovir. Radiographic findings may be absent or may demonstrate diffuse ground-glass opacities.

Fungal infections

Opportunistic fungal infections are less common than viral infections, but they are associated with higher mortality. Fungal pneumonias usually occur 10-60 days following transplant and more commonly involve the transplanted lung. The most common findings of fungal infection on CT scans are a combination of nodules (multiple, variable sizes, irregular margins), consolidation, and ground-glass opacification. Pleural effusion also is common (63% of cases).

Aspergillus infection

Locally invasive or disseminated Aspergillus infection accounts for 2-33% of posttransplant infections and 4-7% of deaths in patients who undergo lung transplants. Aspergillus infection most commonly is characterized by local invasion of a necrotic bronchial anastomosis (ie, ulcerative tracheobronchitis), which typically occurs within 4 months of transplantation. Inhaled amphotericin B is often used in the immediate posttransplant period to help eliminate this complication. [57] Patients are also discharged on voriconazole as daily prophylaxis for the first year. Long-term use of voriconazole may be associated with an increased incidence of cutaneous squamous cell carcinoma in lung transplant patients. [59]

Pneumocystis jiroveci pneumonia

Patients who have undergone lung transplant procedures have an increased susceptibility to P jiroveci infection, but prophylaxis with trimethoprim-sulfamethoxazole is effective in preventing the infection (incidence is nearly 0%). [57] Without prophylaxis, the incidence of P jiroveci infection approaches 90%.


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